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key lime cupcakes garnishes with crumbs and key lime slices
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4.74 from 15 votes

Key Lime Cupcakes

Take a tropical vacation with these delicious and moist Key Lime Cupcakes topped with a key lime buttercream frosting and graham cracker crumbs!
Prep Time15 mins
Cook Time15 mins
Total Time30 mins
Course: Dessert
Cuisine: American
Servings: 12 cupcakes
Calories: 511kcal
Author: Amy Nash



  • ½ cup butter room temperature
  • 1 cup granulated sugar
  • cup sour cream room temperature
  • ½ teaspoon vanilla extract
  • 1 Tablespoon key lime zest about 4 key limes
  • 3 egg whites room temperature
  • 1 ½ cups all-purpose flour
  • 2 teaspoons baking powder
  • ¼ teaspoon salt
  • 4 Tablespoons whole milk room temperature
  • 4 Tablespoons key lime juice

Key Lime Frosting

  • 1 cup butter room temperature
  • 4 cups powdered sugar
  • 3-4 Tablespoons key lime juice
  • 1 teaspoon key lime zest plus more for garnish
  • ¼ cup graham cracker crumbs
  • ½ teaspoon vanilla extract
  • Pinch of salt
  • Thinly sliced half-circles of key limes for garnish



  • Preheat the oven to 350 degrees F.  Line a cupcake pan with 12 cupcake liners.
  • In a large bowl, cream together the butter and sugar until light and fluffy, about 3-4 minutes.
  • Add sour cream, vanilla extract and and key lime zest and mix until combined.
  • Mix in egg whites two at a time, mixing well after each addition and scraping down the sides of the bowl as needed. 
  • Whisk together the flour, baking powder and salt in a separate bowl, then add alternately with the milk and key lime juice, mixing between each addition until combined and scraping the sides of the bowl as needed.  
  • Fill the cupcake liners about three quarters full.  Bake for 15-17 minutes, or until the top springs back with a touch or a toothpick inserted in the center of a cupcake comes out clean with just a few crumbs.  Cool completely before frosting.


  • Beat the butter using a hand mixer or stand mixer until smooth.
  • Add the powdered sugar in two batches, mixing on low speed until combined. 
  • Add the key lime zest and 3 tablespoons of the key lime juice, mixing until combined.  Add more key lime juice as needed to reach desired consistency.
  • Transfer the frosting to a piping bag fitted with a decorative tip.  Pipe the frosting onto the cupcakes, then press graham cracker crumbs around each cupcake and sprinkle with additional key lime zest, if desired, and stick a thin slice of key lime on top for decoration.


Serving: 1cupcake | Calories: 511kcal | Carbohydrates: 71g | Protein: 3g | Fat: 25g | Saturated Fat: 15g | Polyunsaturated Fat: 1g | Monounsaturated Fat: 6g | Trans Fat: 1g | Cholesterol: 65mg | Sodium: 354mg | Potassium: 67mg | Fiber: 1g | Sugar: 57g | Vitamin A: 762IU | Vitamin C: 3mg | Calcium: 65mg | Iron: 1mg